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There are really two separate problems here, the road and the vehicle. The road first:
Given that the road may be a thousand kilometers long with very low traffic, minimizing the cost per road-kilometer is key, much more than minimizing the cost per vehicle-kilometer. That's why we're in agreement on unpaved roads, instead of railroads, which use less energy per kilometer. I'd bet that the tracks GW is talking about were produced over many years of use, instead of being manufactured on purpose. So we know they work, but maybe they're not the best thing for Mars. My reason for saying that is twofold: Firstly, Mars dirt might not be hard like dried Earth dirt is. There's not water on Mars like on Earth. Exposed dirt here becomes something like a sun-dried brick after a while. I'm no geologist, but in places on Mars without ice in the regolith might be pretty soft. The Wiki article on "Martian Soil" suggests that the outer layer of Mars' soil is mostly sandy. This makes sense if you consider that there's no water or organic life to further break up the rocks or consolidate them.
This is why I'm not a big fan of what GW is proposing: I don't think that the planetary surface is reliably strong enough to keep from falling in. Especially not with multiple usage. I like your proposal for automated steering. But I think it's better to base it on a brick-based rail system driven down into the sand or regolith than on a rut-based system.
The vehicle:
I think the vehicles will probably be on the small side. Economies of scale with increasing numbers of production, plus a smaller vehicle will have more uses. A small engine could be used in manner rovers and unmanned cargo transport, and smaller vehicles will be useful for frequent intracolony transport as well as for transportation between colonies. I'm thinking something with an internal volume comparable to a large SUV or a small-ish van. Chemically fueled, probably methanol and NOx or LOX. I'm thinking that there's no way around using cryogenics here, but instead of shying away from it we should just insulate and accept that there's going to be some boiloff of the LOX.
-Josh
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You know when were looking at chemical fuels for a ground vehicle the usual quest for maximum chemical energy density that dominates in a rocket engine is no longer of much importance, the fuel mass is no longer the dominant fraction of the vehicle and because were staying in contact with the ground we do not have the tyranny of the rocket equation.
I think this will push LoX out of the running as an oxidizer to be replaced with Hydrogen-peroxide.
Note that I'm still on the side of batteries, and would use a Radio-Isotopic-Sterling generator as a second choice over chemical. Hauling the Oxidizer with you is just so impractical. Batteries are competing ON EARTH with vehicles that get to suck their oxidizer in for FREE, take that advantage away and chemical combustion would be immediately obsolete on earth even at the current low gas prices.
The smaller the vehicle gets the worse the chemical solution looks, a chemical combustion heat-engine gets less efficient when small, the fuel/oxadizer get harder to keep at proper temperatures etc. The battery electric solutions remain very robust at small size.
I envision two sizes of small vehicle being ideal
Crock-rocket bike - either a mountain bike or a wide-wheel dirt-bike type vehicle, capable of carrying only 1 person max but so small and light that it is man-liftable and thus incapable of becoming stuck. It has a battery pack but no computer systems, the Astronauts suit would contain a chest mounted cable that plugs into the bike to augment their life-support pack battery and to display the battery power remaining on the bike. Range could be around 10 km and the intended role is as geologic survey on roughest terrain and self-rescue vehicle.
ATV - a larger 4 wheeled vehicle, carries 1 person normally and a second in emergencies by having them strapped to the rear cargo frame. In addition to the electric suit plug-in their would also be a compressed 1-2 kg O2 bottle to again augment suit endurance, normal operations would be for astronauts to use the vehicle oxygen first and keep their suit oxygen in reserve. The bike can be carried on the cargo frame to provide a back-up vehicle. The ATV would be significantly computerized and carry it's own radio and could be tele-operated and camera equipped to go and pick up someone, the rear and forward cargo racks may be be forklift like and able to pick up and deposit standardized mini pallets of ~100kg onto the ground.
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I dunno. Josh may be right about the loose sand vs hard-dirt (moisture) effect. Depends upon what else Curiosity might find, I guess. If they will look for it.
Other than that, you can build any size vehicles you want. Pick a wheel spacing. Then stick to it, just like the Romans did.
Which is exactly why US and European railroad gauge distances are all 4 ft 8.5 inches. That's the chariot wheel spacing that is wide enough, so that two horses pulling the chariots will not stumble in the wheel ruts left by said chariots.
So, therefore, our railroad gauge was quite literally set by two horses's asses! Which just goes to prove that the evil men do lives long after them.
GW
PS - I double-dog dare anybody to tell a tale better than THAT one! And, it's a true tale! This is your heritage; it is where we came from.
Last edited by GW Johnson (2014-12-26 17:40:45)
GW Johnson
McGregor, Texas
"There is nothing as expensive as a dead crew, especially one dead from a bad management decision"
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GW-
Definitely one of many things to keep an eye out for. Mars is gonna need a bunch of engineers! Lately my thoughts have been going in the direction of thinking that we consistently underestimate the amount of work that needs to be done to establish a Martian colony.
Impaler-
I think this will push LoX out of the running as an oxidizer to be replaced with Hydrogen-peroxide.
It turns out that there's an astoundingly small number of oxidizers to choose from. Take a look at what Wikipedia says about making H2O2: http://en.wikipedia.org/wiki/Anthraquinone_process. This reaction uses several organic compounds which are difficult to synthesize without crude oil around and will likely be destroyed at a non-negligible rate by the Hydrogen Peroxide. Plus, we don't use it on Earth, for anything. Even in racing they use Nitrous Oxide, a gas, over this. The reason is that it's not very storeable, especially at high concentration, and I know GW's got something to say about that if you want to ask him!
Let's take a look at some other oxidizers: You have nitrous oxide, N2O, which has the same boiling temperature as LOX only it has less oxygen and is harder to make. You have nitric acid, which is corrosive plus somewhat difficult to make (You need to make Nitrogen Monoxide, first, by burning ammonia in oxygen at 900 C over a Pt catalyst; Burn this in Oxygen even more to NO2; Then dissolve this in water to react it to nitric acid.
Then there's NO2 itself; Same problems as Nitric acid, but it's more volatile.
Then there's Hydrazine, used as a monopropellant. I'd say it's easier to make hydrazine than nitric acid, but that's just a guess, and I don't know by how much.
Then there's ammonium nitrate. Stable, if solid, not too hard to make once you have the nitric acid, and no gaseous byproducts. But you do still need the nitric acid.
Then you have your hypochlorites, chlorites, chlorates, and perchlorates. Nasty and toxic, plus energy intensive to make, all of them.
Then you have chlorine, toxic and corrosive; Fluorine, which is worse in every way. Sulfur, which is bad for most engines, a solid, hard to find, and very low energy. There's thermite too, but that's not really usable at controlled burn rates.
Batteries are pretty hard to build and require specialized materials. Ditto for fuel cells.
You might not agree, but I think I've been led to methanol-LOX/GOX by a pretty rational thought process.
-Josh
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China's first sea-crossing high-speed railway
https://english.news.cn/20220903/f834cc … 035/c.html
As the cost of living bites, Spain launches FREE train tickets for journeys under 188 miles
https://www.dailymail.co.uk/travel/trav … -rail.html
Can high-speed rail finally become a reality in the U.S.?
https://www.greenbiz.com/article/can-hi … reality-us
Ingenuity Helicopter Marks 30 Flights on Mars
https://www.extremetech.com/extreme/339 … ts-on-mars
Some other discussion on newmars forum
Tunnel Transportation on Earth, Mars or Luna
https://newmars.com/forums/viewtopic.php?id=9843
Long Range Rover
https://newmars.com/forums/viewtopic.php?id=7494
Automobile Updates
https://newmars.com/forums/viewtopic.php?id=9967
Human Business and flight plan for mars
https://newmars.com/forums/viewtopic.php?id=8821
Last edited by Mars_B4_Moon (2022-09-03 12:44:03)
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How would husbands and wives talk as they drive on difficult Mars roads, would the conversation be something like Earth?
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DARPA Is Considering Putting Trains on the Moon, Needs Someone to Build It a Railway First
https://www.autoevolution.com/news/darp … 31123.html
another discussion sometimes the use of foreign words, Seilbahn borrowed from German or téléphérique to take the French designed version of the cable sky transport. The French Vanoise Express cable car carries 200 people in each cabin, the Shinhotaka Ropeway carries 121 people in each cabin at Mount Hotaka in Japan and in Stanserhorn in Switzerland they have transport which carries up to 60 persons
something more simple than a complex underground subway metro system on Mars? skytram, cablecar
http://newmars.com/forums/viewtopic.php?id=10460
back on Earth
Spanish infrastructures: a record €2.7 bn in high-speed trains, first roads in a decade
https://thecorner.eu/news-spain/spain-e … ade/72503/
from last year in Chile
Santiago Metro Line 2 extension inaugurated
https://www.railwaypro.com/wp/santiago- … augurated/
Exploring the Unusual Kolsås Line in Oslo, Norway
https://www.youtube.com/watch?v=d18XAClHnNc
Getting Around Busan in South Korea – Public Transport Info
https://blog.trazy.com/getting-around-b … port-info/
the South Korean mapped
https://korearailway.com/en/route-map-b … uth-korea/
Last edited by Mars_B4_Moon (2024-04-20 14:36:15)
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